We've all got a few pennies down the back of the sofa or at the back of drawer but a few may be worth a small fortune.

Of the billions of coins in circulation there are a few hundred thousand which are worth more than the price stamped on it, some because they have small errors or imperfections and others because they were produced in small numbers.

Polymer banknotes have been making headlines by fetching eye-watering sums online since the Bank of England launched the new £5 back in September.

But it isn't just the brand-new fiver which is worth a pretty penny, apparently, the Mirror reports .

Thankfully, though, this isn't the only way you can pocket a cool sum of cash.

There are plenty of other valuable coins out there.

Here are a few of them:

Royal Arms £1

The Royal Arms is a common design which is sometimes ignored, but remember to look out for one with a 2008 date – that's actually the fourth rarest and worth about £5.99 to a collector.

Edinburgh £1

The 2011 Edinburgh design is the only £1 coin with a mintage below 1million according to Coin Checker – but while its classed as 'valuable' it'll only fetch in around £3-5 on eBay.

Commonwealth £2

A special coin minted to commemorate the Northern Ireland 2002 Commonwealth Games is one of the rarest £2 out there, as fewer than 500,000 were minted. They can sell online for anything between £15 and £25.

‘Typo’ Guy Fawkes coin

The Royal Mint released a commemorative 50p in 2005 on the 400th anniversary of the Gunpowder plot but some of those had a slightly embarrassing typo and read ‘Pemember, pemember the Fifth of November’. They sell online for between £5 and £7, typically.

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Charles Dickens £2

These were released in 2012 to commemorate the 200th birthday of the famous author, with the reverse of the coin featuring the titles of his better known books. These can now sell online for around £4, sometimes more if in particularly good condition.

Dateless 20p piece - £100

When the Royal Mint redesigned the 20p piece in 2008 it decided to switch the date from the back of the coin to the front.

However, between 50,000 and 200,000 coins were produced with no date on after an error at the Mint mismatched the old and new designs. They now sell for up to £100 for a coin in mint condition.

London Olympic 50p coin - £3,000

There were 29 different designs released to celebrate the 2012 Olympic Games, with some produced in smaller numbers than others. A full set normally commands around £35 while some of the more desirable or rare designs such as football, wheelchair rugby, wrestling and tennis can command £3 or £4.

But if you come across an original aquatic coin, showing water passing directly over the swimmer’s face, you've hit the jackpot. Just 600 were released before the design was altered to show a clearly visible face. One of the original coins was recently listed on eBay for £3,000 .

The 1983 ‘New Pence’ 2p coin - £650

After British currency went decimal in 1971, all 2p coins had ‘New Pence’ on the reverse until 1981. The Royal Mint decided to replace ‘New Pence” with ‘Two Pence’ in 1982.

However, in 1983 the Mint accidentally produced a small number that bore the old inscription ‘New Pence’ . These went into special collectors sets, but if you do find one that made its way into circulation it could be worth up to £650.